Phase separation after chloroform addition was not particularly good. Aqueous phases in sample 424 was a bit cloudy (salty?) with no defined interphase. The remaining two samples did exhibit a defined interphase and were the aqueous phases were less cloudy than sample 424, but were far from ideal.

Quantified RNA using Roberts Lab Qubit 3.0 with the Qubit RNA high sensitivity kit. Used 5uL of each sample.

RESULTS

No detectable RNA in any samples. Samples were discarded.

As has been the case for all samples in this project, RNA isolation methodologies have produced wildly inconsistent results.

Due to difficulties getting RNA from hemolymph samples stored in RNAlater, Grace is testing out lyophilizing samples before extraction. Who knows what impact this will have on RNA, but it’s worth a shot!

Isolated RNA from three crab hemolymph samples preserved in RNAlater (Test 1, Test 2, Test 3) that had been lyophilized overnight last week.

RESULTS

So, this little test demonstrates that RNA can be isolated from lyophilized samples and extracted with TriReagent. However, I have not evaluated RNA integrity on the Bioanalyzer. I think Grace has some additional samples she wanted to test this method on, so I think we’ll wait until there are more samples before we use the Bioanalyzer.

Oddly, one sample (crab_506) appears to be shifted, relative to the other three, despite exhibiting the same peak/banding pattern. Not sure what would cause something like this; contaminants?

Regardless, we finally have clean RNA and have a usable Bioanalyzer profile to use for reference for crab RNA.

NOTE: The lanes marked with red on the gel representation image indicate that a ribosomal integrity number (RIN) could not be calculated. This is to be expected! The RIN is based on the expectation of two rRNA bands. The anomaly is sample crab_451 – a RIN was actually determined for that sample!

Crab hemolymph had been collected (100uL?) and preserved with 1mL (?) of RNAlater. Grace pelleted the samples, removed the supernatant, and stored the pelleted material at -80C. Here’s what that looked like:

RESULTS

Overall, the isolation looks pretty good. The purity looks good (NanoDrop 260/280 ratios) and the absorbance peak at 260nm is exactly where we would want/expect it to be.

The yields (according to the Qubit) are OK. They range from ~37ng – 350ng.

The important part is that this method produced clean RNA, which means the quantification is believable. I think Grace’s earlier RNA isolations using RNAzol RT had too much contamination carried over, leading to incorrect quantification measurements.

Going forward, I think we need to use some sort of isolation kit, however, we will be testing out good, old TriReagent as well.

The tubes hold max of 1600 ul. Will know on Sun or Mon if either crab is infected w Hematodinium.

Tracking info to follow.
Pam

Samples were stored at 4C O/N.

Here’s what the samples looked like before processing:

The samples are extremely cloudy. I’m not sure if this is expected.

Processed samples using RNAzol RT (MRC) according to the manufacturer’s protocol for Total RNA Isolation.

Pelleted samples at 5000g for 5 mins and the samples looked like this:

Decided to pellet samples for an additional 10mins. The pellet was more compact. Transferred supernatant to clean tube, since it seemed to contain “debris” (maybe cells?). Processed pellet with RNAzol RT. Brief rundown of procedure (all steps at room temp):

This is not normal. Usually the supernatant is the clear portion, while the blue layer is below that.

Transferred 750uL of the clear portion to clean 1.7mL tube.

Added equal volume of isopropanol, mixed by inversion. Appeared to be a very high amount of genomic DNA precipitation visible in the tube.

Incubated for 10mins.

Centrifuged 12,000g, 15mins.

Samples looked like this:

It appears that the nucleotides (the white interphase) are suspended on a “cushion” of higher density solution, instead of pelleted at the bottom of the tube.

Removed/discarded higher density solution, leaving the white layer on the bottom of the tube.

Centrifuged 12,000g, 15mins.

Discarded supe.

Washed pellet with 75% ethanol.

Centrifuged 8,000g, 3mins.

Repeated Steps 12, 13, & 14, 1x.

Discarded ethanol.

Resuspended RNA in 50uL 0.1% DEPC-treated H2O. Pellets did not solubilize on their own. I dispersed the pellets by repeated pipetting (P200). Remaining insoluble material was pelleted (12,000g, 30s) and supernatant was transferred to a new 1.6mL tube.

RNA was quantified using the Qubit 3.0 and the Qubit HS RNA Assay. Used 5uL of each sample.